In order to install an SSL cert after purchasing follow the steps below

This article assumes you have already generated a CSR and purchased as certificate. If you have not done this, please see the related articles

1) Log into CPanel
2) Click SSL/TLS under the Security section
3) Click on Certificates 'Generate, view, upload, or delete SSL certificates.'
4) If your provider has issued you with the just text that makes up the cert, paste it in the box provided and press 'Save Certificate'
or If your provider has issued you with a .crt file, click Browse under 'Choose a certificate file' and then click Upload Certificate